<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>边框border</title>
	<style type="text/css">
		.border{
			width: 200px;
			height: 200px;
			/*border: 1px solid red;*/
			/*按照三要素来编写border*/
			/*border-width: 4px 10px;
			border-style: solid dotted double dashed;
			border-color: green red purple yellow;*/

			/*按照方向来编写border*/
			/*
			border-top-width: 4px;
			border-top-color: red;
			border-top-style: solid;

			border-bottom-width: 4px;
			border-bottom-color: red;
			border-bottom-style: solid;
			*/
		}
		input{
			/*清除默认样式*/
			/*border: none;*/
			/*或者*/
			border: 0;
			/*清除外线*/
			outline: none;
		}
		.username{
			width: 180px;
			height: 40px;
			font-size: 20px;
			padding-left: 10px;
			border: 1px solid #666;
		}
		.username:hover{
			border: 1px solid orange;
		}
	</style>
</head>
<body>
	<!-- 三要素： 粗细（width）  样式 (style) 颜色 (color)-->
	<div class="border"></div>
	<input type="text" name="" class="username">

</body>
</html>